Automatic tissue processor

ABSTRACT

A machine for processing histological tissue having a tissue carrier basket suspended from a turntable overlying a plurality of beakers suspended from a carrier plate. The turntable is raised, indexed, and lowered by a suitable driving mechanism to move the tissue basket sequentially through the beakers. Three timers can each be programmed to control the movement of the turntable to provide various different cycles for processing the tissue. Some of the beakers are received in individual thermal baths to heat and control the temperature of the substances received in the beakers for treating the tissue.

United States Patent 1 1 Lipshaw 1 Oct. 2, 1973 AUTOMATIC TISSUE PROCESSOR [76] Inventor: Julius Lipshaw, 7446 Central Ave.,

Detroit, Mich. 48210 [22] Filed: Sept. 1, 19711 [21] Appl. No.: 177,020

118/425, 118/426, 211/83, 219/432, 220/234 [51] Int. Cl. B05c 3/04 [58] Field of Search 220/234; 211/71,

21 l/74.4, 77.83; 248/27, 311, 145.6; 269/40; 40/1 NQ; 118/500, 503, 50, 50.1, 423, 425.6, 426, 429.5; 29/433; 134/80; 219/285, 433,

[56] References Cited UNITED STATES PATENTS I 586,195 7/1897 Monroe 220/23.4 1,622,075 3/1927 Atwater 2,532,244 11/1950 Pasmore ...2ll/71UX 2,534,680 12/1950 Poirier et al. 211/77 X 2,566,430 9/1951 Sobers 211/77 X 2,662,644 12/1953 Alexander 211/77 Primary Examiner-Morris Kaplan Attorney-Barnes, Kisselle, Raisch & Choate [57] ABSTRACT A machine for processing histological tissue having a tissue carrier basket suspended from a turntable overlying a plurality of beakers suspended from a carrier plate. The turntable is raised, indexed, and lowered by a suitable driving mechanism to move the tissue basket sequentially through the beakers. Three timers can each be programmed to control the movement of the turntable to provide various different cycles for processing the tissue. Some of the beakers are received in individual thermal baths to heat and control the tem-' perature of the substances received in the beakers for treating the tissue.

6 Claims, 11 Drawing Figures CU zo VAUJ UM /4 2 5 o BY PASS 2 2 'Pmmmw "2 3,762,362

SHEET 2 UF 5 0 iiii INVENTOR. JULIUS Ll PSHAW ATTORNEYS PATENTEDUBI 2 3, 762.362

SHEET 3 OF 5 Station J INVENTOR. JUL 1 US Li PSHAW AT'TOR NEYS PAIENTED 2W3 3.762.362

sum u or 5 INVENT R. JULBUS LIDSHA ATTO RNEYS AUTOMATIC 'IISSIUE PROCESSOR This invention relates to the preparation of histologi cal tissue for microscopic examination and more particularly to a machine for automatically processing histological tissue.

Objects of this invention are to provide a tissue processing machine in which the beakers cannot be inadvertently dislodged from the machine, the processing liquid in a thermal bath can be readily changed without the necessity of cleaning the thermal bath, the processing cycle can be readily changed by the use of three cycle timers and individual thermal baths, and the processing machine is of economical construction and assembly, relatively maintenance free and readily serviceable.

These and other objects, features, and advantages of this invention will be apparent from the following description, appended claims, and accompanying drawing in which:

FIG. I is a front elevational view of a tissue processing machine embodying this invention.

FIG. 2 is a fragmentary side view of a thermal bath with a beaker therein used in the tissue processing machine.

FIG. 3 is a fragmentary side view of a portion of one of the timers of the tissue processing machine.

FIG. 4 is a rear view with portions broken away of the tissue processing machine.

FIG. 5 is a fragmentary top view of a beaker carrier of the tissue processing machine with a beaker received therein.

FIG. 6 is a sectional view generally on line 6-6 of FIG. 4. I

FIG. 7 is a fragmentary enlarged sectional view on line 7-7 of FIG. 6.

FIG. 8 is an enlarged sectional view on line 8-8 of FIG. 4.

FIG. 9 is a sectional view on line 9-9 of FIG. 8.

FIG. I6 is a fragmentary side view partially in section of the tissue processing machine illustrating a portion of the apparatus for evacuating a beaker.

FIG. I I is a fragmentary side view partially in section of the tissue processing machine illustrating a turntable with a beaker cover overlying a beaker.

REFERRING IN MORE DETAIL TO THE DRAWINGS FIG. I illustrates a tissue processing machine 26 embodying this invention which has a base cabinet 22 adapted for resting on a table top, a carrier plate 24 for a plurality of beakers 26 preferably of stainless steel, and a turntable 2 with a plurality of beaker covers 32 and an evacuation beaker cover34. At least one tissue basket 35 (FIG. 4) is also carried by turntable 28 which is sequentially raised, indexed, and lowered to process histological tissue in basket 35 by progressively exposing the tissue to processing liquids in beakers 26. The intermittent indexing of turntable 28 is programmed and controlled-by electric circuitry including various timers or timing clocks. A fast processing timer 36 and a conventional processing timer 38 are mounted in the front face of cabinet 22 behind transparent plexiglass panels 46 each connected by a piano hinge 42 to the front face of the cabinet. A staining timer 44 is mounted on a sidewall of cabinet 22. The programming of timers 36 and 38 can be readily varied and adjusted to suit various processing cycles by the displacement of timing tabs 46 (FIG. 3) of the timers. The desired timer I is selected by either a switch 48 on the front face of cabinet 22 or a switch 56 on the side face thereof. Switch 48 selects either timer 36 or 38 and switch 56 selects timer 44. A vacuum pump connected to beaker cover 34 for evacuation of a beaker 26 is controlled by a switch 52 on the front face of cabinet 22 and the extent of the vacuum produced by the pump is indicated by a guage 54 mounted thereon. Manual operation of the raising, lowering, and indexing of turntable 28 is controlled by a switch 56 on the front panel of cabinet 22.

As shown in FIGS. I, 4, and 5, beakers 26 have rim flanges 58 and are suspended from circular beaker carrier plate 24 through circumferentially spaced apertures 66 in the carrier plate. Beaker carrier plate 24 has 12 apertures 66 which provide machine 26 with 12 work or processing stations which are numbered for reference clockwise beginning with the station immediately to the left of the center of the front of machine 26 as viewed in FIG. I and indicated in FIGS. I and 6. Beaker carrier plate 24 is supported by a plurality of spacer rods 62 secured thereto by screws 64 on a circular mounting plate 66 fixed to the top of cabinet22. Apertures 66 each have a generally radially outwardly opening slot 67 through which a handle 68 on a beaker 26 can pass when the beaker is inserted into and removed from carrier plate 24. As shown in FIGS. 4 and 5, each beaker 26 can be retained on carrier plate 24 by rotating the beaker so that the upper end of handle 68 provides a stop 69 underlying a portion of the carrier plate. As shown in FIG. 4, stop portion 69 of handle 68 is spaced below flange 58 so that it will lie closely adjacent the lower face of carrier plate 24 when beaker 26 is rotated to retain the beaker in the carrier plate.

As shown in FIG. 2, a thermal bath 76 with a generally cup-shaped body 7I can be inserted between beaker carrier plate 24 and mounting plate 66 to underlie an aperture 66 and receive a beaker 26 therein. Cupshaped body 7I is preferably made of cast aluminum and has an electric heating element (not shown) therein for heating substances in a beaker 26 received in the body. The heating element is thermostatically controlled and connected to a source of electric current through a power cord 72 and a receptacle outlet 74 mounted in a sidewall of cabinet 22 (FIG. I). Thermal bath 76 has a handle 76 fixed to body 7I and a slot 78 in the sidewall of the body to provide clearance for the upper portion of a handle 68 of a beaker 26. There is only a slight clearance between the upper edge of thermal bath 76 and carrier plate 24 so that when a beaker received in body 71 is rotated so that it is retained in the carrier plate, the thermal bath is also retained on mounting plate 66 and cannot be removed from between the carrier and mounting plates.

As shown in FIGS. 4 and 6, turntable 28 is raised and lowered by an elevator mechanism 86 with a lifting tube 82 fixed at one end to the turntable and telescopingly received over a driving and guide tube 84 supported at its lower end by a mounting bracket 86 fixed to the underside of mounting plate 66. Lifting tube 82 is extended and retracted by a Y-shaped fork 96 bearing on a collar 92 fixed to the lower end of tube 82. One end of fork 96 is pivotally connected by a pin 94 to a bracket 95 fixed to mounting plate 66 and the tines of fork 96 underlie collar 92 and bear thereon through roller bearings 96 mounted on the ends of the tines. The tine end of fork is raised and lowered (as shown in solid and broken line positions in FIG. 4) by a drive motor 98 (FIG. 6) secured to mounting plate 66. Motor 98 is operably connected to fork 90 through a gear reducer 100 with a crank 102 keyed to its output shaft 103. Crank 102 is connected to fork 90 by an arm 104 pivoted at one end to the crank and at the other end to an intermediate portion of the fork. The raised and lowered positions of turntable 28 are sensed by limit switches 106 and 108, the actuator arms of which are tripped by a pin 110 fixed to fork 90. Limit switches 106 and 108 are secured to a bracket 112 fixed to mounting plate 66.

Whenturntable 28 is in the lowered position, it can be axially reciprocated or jogged by a jogging mechanism 114, as shown in FIGS. 4, 6, and 7. Jogging mechanism 114 has a drive motor 116 mounted by a bracket 118 on mounting plate 66. Motor 116 reciprocates lifting tube 82 and hence turntable 28 through an actuator arm 120 and an eccentric 122. Actuator arm 120 is mounted for pivotal movement by a pin 123 received in a bracket 124 fixed to mounting plate 66. When turntable 28 is lowered, one end of actuator arm 120 underlies and bears on collar 92 fixed to lifting tube 82. An adjustable cam follower 126 is threadedthrough the other end of actuator arm 120 and bears on a roller bearing 128 mounted on eccentric 122 which is keyed to the output shaft of motor 116. The jogger and elevator drive motors 116 and 98 and their associated drive mechanisms are enclosed between beaker carrier plate 24 and mounting plate 66 by a continuous circular sidewall 130 telescoped over a hoop 132 fixed to the mounting plate.

Turntable 28 is indexed by a geneva movement 134 connected to the lower end of drive tube 84 as shown in FIGS. 4 and 9. Geneva movement 134 has a follower wheel 136 and a locking plate 138 connected to a retaining ring 140 by screws 142, all three of which are connected to the lower end of drive tube 84 by a key 144 received in a groove 145. Follower wheel 136 is driven by a motor 146 mounted on bracket 86 through a drive pin 148 carried by a locking cam 150 keyed to the drive shaft of the motor. As shown in FIG. 8, drive pin 148 is received serratum in each of twelve equally angularly spaced slots 152 in follower wheel 136. There are the same number of slots 152 in the follower wheel as there are processing stations. Cam lock 150 has a concentric surface 154 adapted to slidably engage serratum each of a plurality of mating surfaces 156 on locking plate 138 to prevent rotation of turntable 28 when drive pin 148 is disengaged from slot 152 of follower wheel 136. Cam lock 150 also has a relief surface 154 which disengages from locking plate 138 and thereby releases follower wheel 136 so that it can be rotated by drive pin 148. The angular position of turntable 28 is sensed by two limit switches 158 and 160 mounted on a bracket 162 fixed by a screw 164 to mounting plate 86. Limit switch 160 is tripped by one of a plurality of circumferentially spaced buttons 166 fixed to follower wheel 136 everytime the follower wheel is indexed one processing station by drive motor 146. Limit switch 158 is tripped by a button 166 fixed to follower wheel 136 everytime the follower wheel is rotated one complete revolution. Geneva movement 134 and limit switches 158 and 162 are shown in FIGS. 8 and 9 in the position they assume when evacuator beaker cover 34 is in processing station number 12. The lower end of drive tube 84 is carried for free rotation on mounting plate 86 by a cylindrical plug 170 which is received in a hole 172 through the plate and retained therein by a retaining nut 174. Plug 170 has a shoulder 176 which receives two wear washers 178 thereon with the lower end of tube 84 bearing on the washers. Relative rotation between drive tube 84 and telescoping lift tube 82 is prevented by a pin 180 threadily received in the lower end of lift tube 82 and projecting into groove 145 which extends the entire length of the drive tube.

As shown in FIG. 4, evacuator beaker cover 34 is coupled with a vacuum pump 182 driven by an electric motor, so that a beaker 26 sealed with the cover can be evacuated. Depending on the particular processing cycle, there may be several evacuator beaker covers 34 mounted on turntable 28, however, for convenience, only one evacuator beaker cover is shown and described. Beaker cover 34 is connected to turntable 28 through a bellows assembly 184 (FIG. 10) which has top and bottom connector plates 186 and 188, a resilient flexiblepreferably metal bellows 190, and a cylindrical shield 192. Top plate 186 is fixed and sealed to the upper end of bellows 190 such as by soldering and is connected to a mounting plate 194 of turntable 28 by bolts and nuts 196. The upper end of cylindrical shield 192 is press fit over a shoulder 198 of upper connector plate 186. Bottom connector plate 188 is fixed and sealed to the lower end of bellows 190 by soldering and is secured to beaker evacuator cover 34 by a retainer nut 200. A seal 202 provides an air tight closure be tween evacuator cover 34 and each beaker 26 which it engages when turntable 28 is in the fully lowered position. Preferably, seal 202 has a ring of sponge rubber 204 with one face adhered to cover 34 with an adhesive and the other face laminated to one face of a ring of neoprene rubber 206. Sample basket 35 is releasably suspended below evacuator cover 34 by a bayonet type coupling. The bayonet type coupling is provided by two diametrically opposed radially outwardly extending pins 208 fixed to basket 35 which can be received in two generally opposed reenterant slots 209 in a basket cover and locating ring 210. Basket cover 210 is secured by retaining nuts 211 to the lower end of a pipe 212 extending through bellows assembly 186 and threadily mounted in top plate 186 thereof for reciprocal movement with turntable 28. Vacuum pump 182 is connected to pipe 212 through a tube 214 telescoped over a pipe 216 which is fixedly mounted adjacent its lower end in plug 170. The lower end of pipe 216 is coupled with pump 182 through a flexible hose 218 and a tee 220. A line 222 connects vacuum gauge 54 with tee 220 and hence pump 182. The upper end of tube 214 is connected to pipe 212 through a swivel coupling 224, flexible hose 226, and appropriate connectors.

Beaker covers 32 are slidably connected to turntable 28 so that the covers will remain on beakers 26 when the turntable. is reciprocated or jogged in the fully lowered position. As shown in FIG. 11, one end of a rod 228 is fixed to a beaker cover 32 by a retaining nut 232 threaded on a reduced shank of the rod extending through a hole 234 in the cover. Rod 228 is slidably received in an oversize hole 235 in plate 194 of turntable 28 and is retained therein by a nut 232 threaded on a reduced shank on the other end of the rod. Turntable 28 has a generally circular cover 236 carried by circui lar mounting plate 194 to overlie and enclose the upper end of the lifting tube and the apparatus connecting the evacuator beaker cover 34 with vacuum pump 182. Mounting plate 194 of turntable 28 is fixed to flanged collar 238 (FIG. received on a shoulder 240 on the upper end of lifting tube'82 and fixedthereto by screws 240.

Histological tissue is usually processed by being placed sequentially in a plurality of different processing liquids and then being impregnated with a wax in liquid form which is subsequently allowed to solidify. This processing can be hastened by being performed in evacuated chambers and by heating some but usually not all of the various liquids. In processing histological tissue in machine 20, the processing liquids are placed in beakers 26 which are inserted clockwise (FIGS. 1 and 6) in the processing stations in the sequence in which it is desired to place the histologicaltissue in the liquids; The wax for impregnation is placed usually in solid form in a beaker 26 which is inserted through carthe electric-heating element in the thermal bath. Similarly, if it is desired to heat any of the processing liquids, they are placed in beakers 26 which are inserted in thermal ba'ths70 .connected to a source of power through machine 20. To assure that beakers 26 do not become dislodged from carrier plate 24, they are rotated so'that their'handles 68 underlie a portion of carrier plate 24 as shown in FIG. 5. Thermal baths70 are also retained in the machine by the rotation of the handles68 of the beakers 26 received in the baths.

Depending on the desired time intervals between the indexing of turntable 28, one of the timers 36, 38, or 44 is selected and programmed in accordance with a predetermined processingcycle. Timer 38 is a 24-hour, 7-day timer with a 24-hour omitting mechanism in which tabs 46 are displaced to control the time interval between the opening and closing of electric contacts in the timer. In timer 38, each tab 46 represents an interval of lSiminutes. Similarly, timer 36 is a 24-hour timer in which each tab 46 represents a 5-minute time interval. Timer 44 is a 1-hour timer which can be adjusted to 1 minute intervals and multiples thereof between the opening and closing of its electric contacts. Through an appropriate control means (not shown) each of the timers can control the amount of time that the histological tissue isretained in a beaker 26 in one of the stations before it is indexed by turntable 28 to the next station. After the timer has been programmed for a particular process, it is energized by actuating-switches 48 or 50. Switch 48 has two on positions and can be manipulated toenergize either clock 36 or 38. Switch 54 has a single "on" position andcan be manipulated to energize clock 44. I l I After-the proper timer is selected, programmed, and energized, the cycle of machine is initiated by manipulation of switches 52 and 56. Switch 52 energizes vacuum pump 182. Switch 56 has two "on positions and in one onTpOsition energizes drive motor 98 to raise and lower turntable 28. In the other "on position, switch'56 energizes drive motor 146 to index or advance turntable 28 when it is in its elevated position. Switch 56 is manipulated to'position evacuator beaker cover 34 in station 12 with turntable 28 in the raised position. In this position, the tissue to be processed is placed in a basket 35 which is suspended below evacuator cover 24. Manual manipulation of switch 56 to index the tissue to be processed in the raised position from station 112 to station 1 and to lower the tissue into station ll trips limit switch 158 which initiates through the control means automatic cycling of the tissue being processed through the remaining stations in accordance with the time intervals determined by the pro gramming of the appropriate timer. The control means uses the signal provided by the change of state of the contacts of the preselected timing clock 36, 3 8, or 44 to automatically raise, index, and lower turntable 28 into each of the remaining work positions.

. The control means energizes motor 98 to raise turntable 28 by rotating crank 102 half a revolution to the generally vertical position shown in solid lines in FIG. 4 which pivotally moves fork 104 in an arcuate path generally upwardly while bearing on collar 92 and raises tube 82 to lift turntable 28. When fork 94 is shifted to the raised position, it trips limit switch 108 which through the control means deenergizes elevator drive motor 98 and energizes drive motor 146 to index evator drive motor 98 to rotate crank 102 half a revolu- I .or advance through geneva movement 134 table 28 one work station. When table 28 is advanced one workst'a tion, limit switch 160 is tripped by a button 166 on follower wheel 136 which through the control means deenergizes indexing drive motor 146 and r'eenergizes eltion to lower elevator 128. As elevator 12 8 becomes fully lowered, fork 90 trips li mit switch 106 which through the control means deenergizes elevator drive motor 98 and energizes jogger drive'moto'r I16 and a to vertically reciprocate ca'rrier basket 3.5 and thereby agitate the histological tissue samples in thebeaker 26 of processing" liquid in which the basket is received. When the preselected timing clock 36, 38, or 44 again changes the state of its contacts to indicate that the time interval for the particular work station has expired, jogger drive motor 116 and the vacuum pump solenoid valve are deenergized through the. control means and elevator drive motor98 is energized. This terminates the evacuation of the beaker receiving the repeated seriatum in accordance with the time intervals,

provided by the preselected timer until the tissue basket is advanced through each work station and received in station 112.

If desired, more than one evacuation beaker cover '34 and bellows assembly 184 can be mounted on turntable 28 so that more than one basket of histological tissue can be processed at the same time in machine 20. If machine 20 is adapted to simultaneously process more than one basket of tissue, the control means must be slightly modified to properly cycle the machine. Suitable modifications will be apparent to those skilled in the art in view of the foregoing description of the operation of the control means andtherefore need not be described in detail herein.

The use of a carrier plate and a beaker with a stop thereon which can be rotated to underlie the carrier plate provides a'tissue processing machine in which the beakers cannot be inadvertently dislodged. The use of thermal baths which releasably receive a beaker therein provides a processing machine in which the particular substance being heated by the thermal bath can be readily changed without the necessity of cleaning the thermal bath. The use of at least three cycle timers and individual thermal baths for each processing substance to be heated provides a processing machine which has great flexibility in accomodating a large variety of different processing cycles. The use of individual removable thermal baths, individual drive motors, and comparatively simple mechanical arrangements for raising and lowering, indexing and jogging the turntable provides a processing machine of economical construction and assembly which is relatively maintenance free and can be readily serviced.

I claim:

1. A histological tissue processing machine having a base, a beaker carrier plate mounted on said base, said beaker carrier plate having a plurality of circumferentially spaced holes therethrough adapted to receive beaker receptacles therein, each of said holes through said plate opening generally radially outwardly through the peripheral edge of said plate, at least one beaker having a flange adjacent itsupper end, said beaker being adapted to be suspended from said beaker carrier by being received in one of said holes with said flange bearing on said beaker carrier plate, and a handle mounted on said beaker below said flange, said handle having a stop thereon adapted to underlie a portion of said beaker carrier plate when said beaker is rotated to a first position to retain said beaker in one of said holes and when rotated to a second position to release said beaker for removal from said beaker carrier plate, whereby said beaker cannot be inadvertently dislodged from said beaker carrier plate when rotated to said first position.

2. The tissue processing machine of claim 1 which also comprises at least one thermal bath adapted to underlie said beaker carrier and to receive one of said beakers received in one of said receptacles, said thermal bath having an electric heating element adapted to supply heat to a substance in a beaker received in said thermal bath. 7

3. The tissue processing machine of claim 1 which also comprises a turntable overlying said beaker carrier, an elevator mechanism connected to said turntable and adapted to raise and lower said turntable with respect to said beaker carrier, an evaeuator beaker cover carried by said turntable and adapted for sealing engagement with a beaker received in one of said receptacles in said beaker carrier, and a laminated seal having a first ring of a resilient sponge rubber material with one face adhered to said evacuator beaker cover and the other face adhered to one face of a second ring of a flexible neoprene material with the other face of said second ring being adapted for sealing engagement with one of said beakers in one of said receptacles when said turntable is fully lowered by said elevator.

4. The tissue processing machine of claim 1 which also comprises a turntable overlying said beaker carrier, elevator mechanism connected to said turntable for raising and lowering said turntable with respect to said beaker carrier, indexing mechanism for rotating said turntable with respect to said beaker carrier when said turntable is in a raised position with respect to said beaker carrier, a plurality of beaker covers and at least one beakerevacuation cover each carried by said turntable for covering beakers received in said receptacles of said beaker carrier when said turntable is in a fully lowered position, jogger mechanism for imparting a slight reciprocal motion to said turntable when said turntable is in a fully lowered position, vacuum producing means adapted to be operably connected with said evacuation beaker cover for evacuating a beaker underlying and covered by said evacuation beaker cover, and at least one basket for histological tissue adapted to underlie said evacuation beaker cover and be releasably suspended from said turntable so as to be reciprocated within a beaker underlying said evacuation beaker cover when said turntable is in said fully lowered position and being reciprocated by said jogger means.

5. The tissue processing machine of claim 4 which also comprises at least three electrically operated timers each having at least one set of electric contacts adapted to change state at each of a plurality of time intervals and an electric control means utilizing the change of state of at least one set of contacts of one of said timers to control said elevator mechanism, said indexing mechanism, and said jogger mechanism to provide a predetermined sequence of raising, indexing, lowering, and reciprocating said table with respect to said beaker carrier to advance said tissue basket through a predetermined plurality of beakers retained in receptacles of said beaker carrier, whereby histological tissue received in said tissue basket can be subjected to a predetermined processing in various preselected liquids retained in said beakers.

6. The tissue processing machine of claim 1 which also comprises a generally cup-shaped body adapted to receive said beaker therein, said beaker received in said cup-shaped body, an electric heating element carried by said cup-shaped body and adapted to be connected to a source of electric power to heat a substance in said beaker, and a thermostatic control carried by said cup-shaped body and electrically connected with said heating element to maintain the temperature of said beaker within predetermined limits when said heating element is connected with a source of power. t 9 *8 

1. A histological tissue processing machine having a base, a beaker carrier plate mounted on said base, said beaker carrier plate having a plurality of circumferentially spaced holes therethrough adapted to receive beaker receptacles therein, each of said holes through said plate opening generally radially outwardly through the peripheral edge of said plate, at least one beaker having a flange adjacent its upper end, said beaker being adapted to be suspended from said beaker carrier by being received in one of said holes with said flange bearing on said beaker carrier plate, and a handle mounted on said beaker below said flange, said handle having a stop thereon adapted to underlie a portion of said beaker carrier plate when said beaker is rotated to a first position to retain said beaker in one of said holes and when rotated to a second position to release said beaker for removal from said beaker carrier plate, whereby said beaker cannot be inadvertently dislodged from said beaker carrier plate when rotated to said first position.
 2. The tissue processing machine of claim 1 which also comprises at least one thermal bath adapted to underlie said beaker carrier and to receive one of said beakers received in one of said receptacles, said thermal bath having an electric heating element adapted to supply heat to a substance in a beaker received in said thermal bath.
 3. The tissue processing machine of claim 1 which also comprises a turntable overlying said beaker carrier, an elevator mechanism connected to said turntable and adapted to raise and lower said turntable with respect to said beaker carrier, an evacuator beaker cover carried by said turntable and adapted for sealing engagement with a beaker received in one of said receptacles in said beaker carrier, and a laminated seal having a first ring of a resilient sponge rubber material with one face adhered to said evacuator beaker cover and the other face adhered to one face of a second ring of a flexible neoprene material with the other face of said second ring being adapted for sealing engagement with one of said beakers in one of said receptacles when said turntable is fully lowered by said elevator.
 4. The tissue processing machine of claim 1 which also comprises a turntable overlying said beaker carrier, elevator mechanism connected to said turntable for raising and lowering said turntable with respect to said beaker carrier, indexing mechanism for rotating said turntable with respect to said beaker carrier when said turntable is in a raised position with respect to said beaker carrier, a plurality of beaker covers and at least one beaker evacuation cover each carried by said turntable for covering beakers received in said receptacles of said beaker carrier when said turntable is in a fully lowered position, jogger mechanism for imparting a slight reciprocal motion to said turntable when said turntable is in a fully lowered position, vacuum producing means adapted to be operably connected with said evacuation beaker cover for evacuating a beaker underlying and covered by said evacuation beaker cover, and at least one basket for histological tissue adapted to underlie said evacuation beaker cover and be releasably suspended from said turntable so as to be reciprocated within a beaker underlying said evacuation beaker cover when said turntable is in said fully lowered position and being reciprocated by said jogger means.
 5. The tissue processing machine of claim 4 which also comprises at least three electrically operated timers each having at least one set of electric contacts adapted to change state at each of a plurality of time intervals and an electric control means utilizing the change of state of at least one set of contacts of one of said timers to control said elevator mechanism, said indexing mechanism, and said jogger mechanism to provide a predetermined sequence of raising, indexing, lowering, and reciprocating said table with respect to said beaker carrier to advance said tissue basket through a predetermined plurality of beakers retained in receptacles of said beaker carrier, whereby histological tissue received in said tissue basket can be subjected to a predetermined processing in various preselected liquids retained in said beakers.
 6. The tissue processing machine of claim 1 which also comprises a generally cup-shaped body adapted to receive said beaker therein, said beaker received in said cup-shaped body, an electric heating element carried by said cup-shaped body and adapted to be connected to a source of electric power to heat a substance in said beaker, and a thermostatic control carried by said cup-shaped body and electrically connected with said heating element to maintain the temperature of said beaker within predetermined limits when said heating element is connected with a source of power. 